Go on a tour and you will never look back. It's THE best way to see any country. The hardtail would be a good idea if you were going for one bike. Probably a more racy hardtail with an air shock up front to save wieght. Hell, my stumpjumper pro weights less than my Surly LHT. For my money though I would get a LHT or Crosscheck so I could have racks and fenders and then just bring some foldable cyclocross tires with me for the mountainbiking if I was going on a long distance tour.
I can't wait untill this summer when I can do some nice touring. As for now though I'll have to settle with my ecology class in Costa Rica in a few days.
I have a feeling I'm going to miss college.